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WinForms FAQ - Serialization

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You do this inorder to ensure that your component gets disposed along with the contained Form (logical parent).

All Form derived classes come with an IContainer field into which many of the .Net components like ImageList and Timer add themselves to. The Form will dispose the contents of this IContainer from within its Dispose.

Scenario 1

In order for your Component to get added to this IContainer list, all you have to do is provide a constructor that takes IContainer as the one and only argument. The design-time will discover this constructor automatically and use it to initialize your component. You should then add yourself to the IContainer in the constructor implementation.

Note that for this to work your Component should not have a custom TypeConverter that can convert your type to an InstanceDescriptor.

Example:


public class MyComponent : Component
{
  public MyComponent()
  {
  }

  public MyComponent(IContainer container)
  {
    container.Add(this);
  }
}

Scenario 2

Your components might have more constructors besides the default constructor and you might have a custom TypeConverter that provides an InstanceDescriptor to let your designer use a non-default constructor for initializing your component in code.

In this case, the above approach will not work because you do not have an IContainer-argument only constructor.

You now have to recreate what the design-time did for you. You have to provide a custom IDesignerSerializationProvider to do so. The attached ContainerInsertingSerializationProvider class can be used to get the above effect.

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Sometimes you might want to let the designer serializer serialize the changes in base fields via a property rather than the field itself using the AccesssedThroughProperty attribute as follows:


public class MyBaseForm : Form
{
	[AccessedThroughProperty('MyList')]
	private ArrayList myList;
	
	public ArrayList MyList
	{
		return this.myList;
	}
}

Then when the above form is inherited and items get added to the inherited form’s designer, code will be added as follows in the inherited form’s InitializeComponent:


private void InitializeComponent()
{
	... ... ... ...
	this.MyList.Add(aNewItem);
	... ... ... ...
}
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It is normal to have Properties in your Control/Component whose default values are

inherited from some other Control/Component.

In such cases you will normally prevent the designer from storing the property’s

value in code (using either DefaultValue attribute or the ShouldSerializeXXX

pattern). However, if that property is Localizable and Localization is turned on,

then the property’s value will be forced to be stored in the resource. This will

break your property-inheritance logic.

For example:


[
Localizable(true)
...
]
public Font MyControlButtonFont
{
	get
	{
		if(this.buttonFont == null)
			return this.Font;
		else
			return this.buttonFont;
	}
	set
	{
		this.buttonFont = value;
	}
}

private bool ShouldSerializeMyControlButtonFont()
{
	if(this.MyControlButtonFont == this.Font)
		return false;
	else
		return true;
}

In the above case the MyControlButtonFont inherits its value from the Font

property, if its value is not set. And you use null to determine whether the value

is set or not.

But when Localization is ON, the property gets SET and you lose the inheritance

logic.

You can avoid this by specifying an AmbientValue attribute for your property, as

follows:


[
Localizable(true),
AmbientValue(null)
...
]
public Font MyControlButtonFont

This will use the AmbientValue as the value to persist when there is default-value

in your property. This will prevent your property from getting SET unnecessarily.

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